đề bài:tìm nghiệm giúp mik với hhu 3$x^{3}$-12$x^{}$=? 3$x^{3}$+12$x^{2}$=? 3$x^{3}$-12$x^{2}$=? 11/10/2021 Bởi Faith đề bài:tìm nghiệm giúp mik với hhu 3$x^{3}$-12$x^{}$=? 3$x^{3}$+12$x^{2}$=? 3$x^{3}$-12$x^{2}$=?
a) `3x^3-12x=0` ⇔`3x(x^2-4)=0` ⇔\(\left[ \begin{array}{l}3x=0\\x^2-4=0\end{array} \right.\) ⇔\(\left[ \begin{array}{l}x=0\\x=-2;2\end{array} \right.\) b) `3x^3+12x^2=0` ⇔`3x^2(x+4)=0` ⇔\(\left[ \begin{array}{l}3x^2=0\\x+4=0\end{array} \right.\) ⇔\(\left[ \begin{array}{l}x=0\\x=-4\end{array} \right.\) c) `3x^3-12x^2=0` ⇔`3x^2(x-4)=0` ⇔\(\left[ \begin{array}{l}3x^2=0\\x-4=0\end{array} \right.\) ⇔\(\left[ \begin{array}{l}x=0\\x=4\end{array} \right.\) Bình luận
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a)
`3x^3-12x=0`
⇔`3x(x^2-4)=0`
⇔\(\left[ \begin{array}{l}3x=0\\x^2-4=0\end{array} \right.\)
⇔\(\left[ \begin{array}{l}x=0\\x=-2;2\end{array} \right.\)
b)
`3x^3+12x^2=0`
⇔`3x^2(x+4)=0`
⇔\(\left[ \begin{array}{l}3x^2=0\\x+4=0\end{array} \right.\)
⇔\(\left[ \begin{array}{l}x=0\\x=-4\end{array} \right.\)
c)
`3x^3-12x^2=0`
⇔`3x^2(x-4)=0`
⇔\(\left[ \begin{array}{l}3x^2=0\\x-4=0\end{array} \right.\)
⇔\(\left[ \begin{array}{l}x=0\\x=4\end{array} \right.\)